This invention relates to a method of manufacturing a hermetically sealed terminal for a quartz crystal resonator or the like which is used in a watch, and more particularly relates to a method of manufacturing a hermetically sealed terminal in which the terminal plate and lead wires are fixed to a casing by an intervening insulated glass material held by a metallic outer frame.
A small quartz crystal resonator used in a quartz crystal electronic watch is shown in FIGS. 1A and 1B. A hermetically sealed terminal is composed of a pair of terminal plates 3a, 3b on which a quartz crystal resonator 2 is fixed electrically and mechanically. A set of lead wires 4a, 4b are brazed to terminal plates 3a, 3b respectively, an outer frame 5 is brazed on the casing 1 in which the quartz crystal resonator 2 is encased and a glass material 6 is held by the outer frame 5.
Conventional manufacturing methods of such hermetically sealed terminals are as follows. After lead wires 4a, 4b are fixed to the outer frame 5 by the glass material 6, the end portion of lead wires 4a, 4b is brazed to terminal 3a, 3b respectively by eutectic silver and copper. Since the lead wires 4a, 4b, the outer frame 5 and the glass material 6 are all heated again when lead wires 4a, 4b and terminal plates 3a, 3b are brazed, these component parts are apt to receive damage by heat shock. Since these component parts are extremely small, it is difficult to braze a pair of terminal plates 3a, 3b and lead wires 4a, 4b at the correct position keeping a precise distance between said terminal plates.
Another conventional manufacturing method of such hermetically sealed terminal is as follows. The terminal plate is made in one body shown by chained line 7 and hatching 3a, 3b in FIG. 1B. After lead wires 4a, 4b are brazed to the terminal plate and fixed to the outer frame 5 by glass material 6, the terminal plate is divided into two parts 3a, 3b taking off the part shown by chained line 7 by grinding or similar operation. After the brazing of the terminal plate and lead wires 4a, 4b, the parts are heated again when the glass material 6 is softened and therefore the terminal plates are apt to deviate from the correct position. This makes it difficult to divide the terminal plate while keeping predetermined accuracy.
As mentioned above, it is difficult to increase the yield rate of oscillator units and to introduce mass production by automatic assembling. For keeping the positional accuracy of the terminal plate, complicated moulds which are used at the heating process have to be prepared, and the working steps are increased.
As a result, it is difficult to increase productivity and to achieve low cost products.